TOPIC: 1999 chev 4.3 L vortec

I did a 4.3 L vortec a couple days ago, Instead of cutting the gasket from flashing I was able to plug part of the idle air hole with jb quick. I think it best to groove the throttle body before pluging the hole. Because where the idle air pathway is it has a narrow spot where you will cut through, and this will need to be patched before pluging the hole. After grooving and patching and leting the patch set up , i took about 3 balls of cotton and stuffed them into the hole where the valve goes, with the t-body turned upside down fill the hole upwards past where the valve will be, then take and melt some candle wax and use enough to coat the cotton so as it will not stick to your jb quick . there will be about 3 eights of an inch of space for the epoxy to fill. After the wax has cooled mix up enough jb quick to fill the hole. After the jb quick has set and cleand off the excess, pull out the cotton balls and scratch out the wax that will be stuck to the bottom of the epoxy, keep digging at the wax until it is all out probably take 10 minutes. I used a piece of high tensile wire bent into shape to use as a pick to dig out the wax. Then drill the eighth inch hole, i drilled it in the part close to where the valve seals. I did not have to use any extra gaskets. I am going to try and add some photos

Hi guy, nice writeup on that 4.3 vortec TB. So here's another way to reduce IAC airflow.

Which bit did ya use? Any pics of the Groove in this one? How did this Chevy respond?

nice play on words of gadgetman, BTW!

Thanks for the pics and input on another technique!

And Welcome to GadgetmanLand!!

Tracy G

To Tracy G , thanks for the welcome to gadgetmanland.
I used the large bit on the groove on the engine side and cut second groove on filter side with smallest bit, the larger bits would cut thru on the filter side. the truck seems to have more low end torque with second groove. Also did the shaping of the throttle plate. I have a long gravel driveway over half mile, with some fairly steep hills, I can put the truck in second gear, it is a 5 speed, and it will pull all the hills without placing my foot on the pedal , and has pulled down to 150 rpm by looking at the tac. , on the steepest grades, and it keeps going, do not hear any pinging or knocking just smooth running on these steep pulls. Sorry dont have photos of the grooves.
On the highway i also notice can be in high gear and moving slow speed and i dont feel the need to shift down, seems to have lots of low end torque. At road speed the pedal has a feather touch needed to accelerate
On my first tank of gas i do not have any extra mileage , actualy lost 2 miles per gallon , was getting 20 now 18 , Since the last tank of gas i have (further reduced the drain from the vacum) ,I will be patient see how things go. .........Greg P

Cool, Greg!

Great write-up and documentation of your mod! Only about one in a hundred go to this level right out of the gate, and they are the ones that usually find great success as a Gadgetman, so GOOD WORK!

As to the MPG's, not to worry. Most vehicles do use a bit more fuel to start with. I recommend running 3-5 tanks, monitoring the mileage along the way. If it's NOT fluctuating, then you can start looking for a vac leak. You may need new O2 sensors as well! All with mileage over 50K (increasing with mileage) are past their service interval, and for good reason (I've done write-ups on this topic).

Anyway, you are doing GREAT!!!

Ron

To Ron, thanks for your input.
On this engine i replaced about a year ago the injectors and gaskets on intake just below the t.body. hope no lekage there , I also replaced some of the vacume hoses at that time, but some may still need to be replaced. I changed out the ox sensors just before the groove , so should not be a problem there.

Hi Greg, sounds like a great power/driveability increase congrats on that!

Just throwin' mud at the wall here...did ya do the computer re-learn process? This one is OBDII so a scantool can tell ya a lot re: sensor values.

If Ron says you're doing great, then you are, he would know!

Tracy G

Hi Tracy G....thanks for your input, i have done the computer re-learn, i have some more news today filled my second tank of gas and it is almost back to 20 mpg it was (19.6) and that was low grade gas . Before with the 18 mpg it was the middle grade gas . The lowgrade did better than the middlegrade. Greg P.

can you tell me if where you buy gas still has emissions control test to past ?
my 1997 without groove has gained 3.7 mpg on Kroger regular gas where emissions test must be passed in Atlanta Ga. I buy same regular gas at Kroger in Savannah Ga but do not get the mpg gain Yes have been asking about the gas difference but no one will talk.
geraldc

To me experience is the teacher. Whatever brand, grade or flavor the engine likes best, well it's telling ya what it likes. I used to have a freind who worked for a gas station chain owner. He worked on replacing underground tanks, and got some industry insider info about our local gas supply. Back then (90's) we supposedly got the gas from Calif. that failed CA gov't standards. I once went to CA. bay area and filled up my tank, drove back to Reno and had noticably better power and longer range on that tank. Car went back to "normal" on next local fillup.

I've read that gasoline is used as a disposal for waste chemicals at refinery. Have no proof, just what I've read/heard. Learned folks have said that Gasoline has hundreds of hydrocarbon molecule combo's. Then ya have winter/summer formula's, and regional emission reg's that cause different "recipies".

Whatever flavor the gas is, the Groove will if done right enhance vaporization to result in more complete combustion --IN the engine instead of the cat's-- equals more efficiency.

Tracy G

I am not sure if they have to pass emissions tests, purchased gas at place called IGA Express , same place both fill ups.

I am writing to report my mileage is now back up to 20 with the low grade gas. I have never got 20 before with low grade gas. Usualy I have to use middle grade to get 20 mpg. The next tank i may try the middle grade and see if any difference.
I have grooved the motor side and filter side of my t.b. , it is possible to cut the filter side groove with flat side of groove facing outward without using the reversed bit.

First cut the groove on the outter side of the throttle plate, then wedge the plate open or remove it, turn the throttle body over and cut the groove from the opposit side useing the first groove as a guide, you are just cutting the same groove twice but from the opposite side, the round part of the groove will be toward the engine.
The 4.3L vortec t.b. has a portion scooped out to direct air to the idle control, I have filled the scooped out part with jb weld leaving a space at the bottom to allow idle air to pass. Hopefuly this will let the air flow more smothly along the walls of the throttle body down to the groove without creating turbulance. Showing some pics of my grooves and the build up of the t.b. wall.

Wishing all happy Holidays and New Year.....Greg P.

thanks again Greg!

your double Groove is Real interesting...so did you do this in 2 stages, main Groove first along w/ IAC mod, re-install, test drive, then add second filter side Groove, or all at one shot?

Does sound like you gained gobs of low end grunt. Ignerant here, is this a V-6 engine? Which truck body is this in? 2wd or 4 wd?

So you/'ve just replaced O2's...good Newer injectors and some intake gaskets...good.

More curiosity--done anything w/ PCV? IF ya have some shots of that mod and the engine overall would help a Pic junkie like me (everyone can read a pic!)

Interesting how yer' gettin' better MPG w/ low grade gas. I could offer guesses as to why, I don't really know. Use whatever works best. Might wanna use Techron once in awhile to keep things clean inside. This one will be interesting to watch to see if you get further gains over time, but an immediate torque gain is satisfying proof to me at least.

Thanks for great pics, Greg,

Keep goin'!!

Tracy G